In the uplifting book, Mortenson shares his story of an effort to climb K2 — the second highest mountain in the world — in his sister’s honor. While climbing the treacherous slope, he had an accident and recounts being rescued by Pakistani villagers who showed him kindness and looked after his survival.

When he was rescued, he promised to return to help build schools for local girls, and now has donated millions of dollars to his charity — The Central Asia Institute — in their honor.

But last night on 60 Minutes, another author, Jon Krakauer, told CBS that Mortenson’s stories, along with his alleged capture by the Taliban, were not true.

“It’s a beautiful story, and it’s a lie,” Krakauer, who original backed Mortenson and his foundation, told CBS’ Steve Kroft.

Mortenson has responded to the accusations against him, saying, “The 60 Minutes program may appear to ask simple questions, but the answers are often complex, not easily encapsulated in 10-second soundbites.”